Systemic methods of drug delivery may produce undesirable side effects and may result in the distribution and metabolization of the drug by physiological processes, ultimately reducing the quantity of drug to reach the desired site. A variety of devices and methods have been developed to deliver drug in a more targeted manner, e.g., locally or regionally, which may address many of the problems associated with systemic drug delivery. Local delivery of drug to some tissue sites, however, has room for improvement, particularly with respect to extended drug delivery with minimally invasive devices and methods with minimum patient discomfort from the presence of the device itself.
For example, interstitial cystitis (IC) is a urological condition characterized by pain, increased urinary frequency, and urgency. This condition may also involve varying degrees of urinary incontinence and sexual dysfunction. IC and Painful Bladder Syndrome include patients with urinary pain not attributable to other causes, such as infection or urinary stones, and are estimated to affect approximately 3 to 8 million people in the U.S. alone, the majority of whom are women. Berry, et al., J. Urol. 186(2):540-44 (2011). IC is a serious condition with unmet medical needs. Other therapies also could benefit from improved intravesical drug delivery devices, particularly where local delivery of a drug to the bladder is preferred or necessary—such as when the side effects associated with systemic delivery of the drug are intolerable and/or when bioavailability from oral administration is too low.
A need exists for an intravesical drug delivery device that is sufficiently small to avoid unnecessary discomfort and pain during and following deployment of the device into patients, that can reduce the number of surgical or interventional procedures required for implantation and delivery of drug over the treatment period—e.g., that provides controlled delivery over an extended period, and that can carry an effective amount of drug for the extended period in a sufficiently small payload volume. In bladder applications, the device desirably should be retained in the bladder and not be excreted before the drug payload can be at least substantially released, even when the drug needs to be delivered over a period of several days or weeks.
Currently, conventional bladder treatments include (1) delivery via instillation, which must be repeated, (2) delivery via conventional devices, which must be re-filled once implanted; (3) delivery via catheters, which provide a path for bacteria to migrate into the bladder, and (4) systemic delivery, which increases the risk of side effects and reduced drug exposure to the target site. In general, better devices are needed for controlled delivery of drug to the bladder. Desirably, the implantable device should be easy to deliver into (and if necessary, remove from) the bladder with reduced pain or discomfort to the patient.
PCT Application Publications WO 2010/151893 and WO 2010/151896 by Taris Biomedical Inc. describe drug delivery devices that provide controlled release of drug from a housing. The device may be free floating in a patient's bladder, yet tolerably and wholly retained in the patient's bladder while locally releasing the drug over an extended period.
It would be desirable, however, to provide new designs of intravesical drug delivery devices, and other implantable devices capable of delivering drugs at effective release rates for a range of different drugs, including those with relatively low aqueous solubility.